Open, as a toothpaste tube (5)
I believe the answer is:
uncap
'open as a toothpaste tube' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for uncap that I've seen before include "open" , "Take the top of the bottle" , "Remove a cover from" , "Remove the lid" , "Remove a top" .)